1. Field of the Invention
The present invention pertains to air pressure sensing probes of the Pitot-Static tube type, and more particularly to such air pressure sensing probes which are inoperative until activated.
2. Description of the Prior Art
Prior erecting type air pressure probes have used stored mechanical energy such as preloaded springs to power probe erection. Other probe designs have used lanyards attached between the probe assembly and the missile launching apparatus to activate the probe after the missile has traveled a predetermined distance from the launcher. Some configurations have included external tear strips attached by a lanyard to the launching apparatus. These tear strips, when torn away, expose the probe mechanism which then activates. Actuation mechanisms using external hardware are useful in air launched missiles, but cannot be used in surface launched missiles where external structure would interfere with the launcher.
Typical prior art air pressure sensing probes are described, for example, in U.S. Pat. No. 3,382,805 to F. H. Swaim. Swaim illustrates an air scoop which is deployed in a rotary manner by a torsion spring. Another prior art device is described in U.S. Pat. No. 3,990,370 to Campagnuolo et al. This device uses an air scoop which is deployed by a lanyard attached between the scoop and launching platform. The scoop defines an internal passageway containing a turbine element which is subjected to slipstream flow as the scoop is deployed. Rotation of the turbine generates the electric current used to arm the ordnance device.